Furnace



Aug. 23, 1938.

G. w. FRANZHEIM FURNACE Filed Nov. 13, 1936 3 Sheets-Sheet l Geonge WFfiwzz/ zem Aug 23, 19380 G. W. FRANZHEIM FURNACE Filed Nov. 13, 1936 3 Shets-Sheet s Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE 4 Claims.

This invention relates to furnaces and more especially to down draft furnaces of that type shown for example in Patent 1,139,660 issued to me on May 18, 1915.

fuel supported on the grate so that said fuel can gravitate into the combustion chamber thereunder.

A further object is to provide fuel feeding means which can be thermostatically controlled whereby a furnace willbe supplied with fuel in the combustion chamber or fire box as needed to maintain a predetermined temperature.

With the foregoing .and other objects in view which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts hereinafter more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

In the accompanying drawings the preferred forms of the invention have been shown.

In said drawings Figure 1 is a view partly in section and partly in elevation of a down draft furnace equipped with the present invention.

Figure 2 is a front elevation.

Figure 3 is a section through a portion of the furnace taken on line 3-3, Figure 1.

Figure 4 is a view similar to Figure 1 showing another form of the invention.

Figure 5 is a front elevation thereof.

Figure 6 is a section through a portion of the furnace taken on line 6-0, Figure 4.

Figure 7 is a view similar to Figures 1 and 4 showing another modification.

Figure 8 is a front elevation thereof.

Figure 9 is a section through .a portion of the furnace on line 9-9, Figure '7, a part of the furnace being shown in plan.

Referring to the figures by characters of reference I designates a boiler or other heat generating unit of the down draft type provided with a lower grate 2 and an upper grate 3, there being a firebox or combustion chamber 4 between these grates which opens into the boiler section 5.

In practice a supply of fuel is fed to the upper grate 3 and is adapted to be sifted downwardly through the grate into the combustion chamber or fire box. An object of the present invention is to provide a means whereby the fuel can be broken up and fed downwardly through the upper grate as needed. One such means has been illustrated in Figures 1, 2 and 3 and includes parallel tubular shafts 6 located above but close to the grate 3. The out ends of these shafts are open so that fresh air may be supplied thereto, this air escaping into the furnace through vents l in the shaft. Agitating teeth or fingers extend I from each shaft, as indicated at 8 and are adapted to work above and close to the spaces between the bars of the upper grate 3, as shown in Figure 1.

Secured to each tubular shaft is a gear 9 forming part of the speed reduction mechanism whereby motion is transmitted from a countershaft l0 and worms II. This counter-shaft is driven by gears 12 from an electric motor l3. The motor can be controlled in its operation by a thermostat 14.

A supply of fuel is deposited on the upper grate and will of course cover the shafts 6 and the teeth or fingers thereon. Fuel on the lower grate will be consumed within the fire box or combustion chamber 4 and the products of combustion will flow outwardly through the sections 5 as ordinarily. When it is necessary to supply additional fuel to the fire box, the motor I3 is operated and motion will be transmitted therefrom through the gearing I2 and the speed reduction mechanism to the shafts 6 which will be rotated slowly, causing the teeth or fingers 8 to plow through the fuel and break it up and .at the same time cause it to sift between the bars of grate 3 and into the combustion chamber.

As the shafts 6 are open at their outer ends and have vents I in them, fresh air can flow through the shafts and into the fuel, this air operating to keep the shafts cool and the air serving to assist in the support of combustion in the fire box or chamber 4.

Instead of providing rotating tubular shafts above the upper grate, shafts 15 can be journalled in the wall of the furnace above the level of the upper grate 3 and these shafts can be formed with crank extensions l6 which .are supported close to the grate 3 and constitute means for agitating fuel and causing it to sift between the bars of the upper grate. These crank extensions Hi can be suitably journalled at those ends thereof within the furnace and as shown at I! in Figure 4.

Any suitable means can be provided for causing the crank-like extensions to oscillate while in use. For example the outer ends of the shafts [5 can be formed with depending arms l8 all of which are connected at their lower ends to a transverse bar l9 mounted in guides 2t and 2|. A spring 22 can be housed in the guide 20 for ex erting a thrust against bar iii to maintain it normally in an intermediate position with arms l8 substantially vertical. A pitman 23 connects the bar l9 to an operating crank 251 which is driven through gears 25 by a thermostatically controlled motor 26.

In this form of the invention the motor, when set in motion, will cause the bar IE to reciprocate and the arms l8 to oscillate. Thus the crank extensions IE will be oscillated within the fuel piled on the grate 3 with the result that this fuel will be broken up and caused to sift between the bars of the grate and into the combustion chamber 4.

A third form of the invention has been illustrated in Figures '7 to 9 inclusive. In this modified structure a shaft 21 is mounted for rotation and reciprocation within a guide at the top of the casing of the boiler. Connected to the bottom of the shaft close to and above the grate 3 is a skeleton wheel or agitator 29 having projecting teeth or fingers 30.

A stationary cam 35 is secured on the boiler and its upper or cam base engages the lower base of a cam 32 which is secured to and moved with the shaft 27. These cams are shown in elevation in Figure 8 and it will be noted by referring thereto that when the shaft is rotated and cam 32 moves therewith, the said cam will ride upwardly upon the lower cam 3i and then gravitate to its lowermost position. Thus the shaft will be reciprocated as it rotates.

For the purpose of actuating the shaft there is provided a worm wheel 33 feathered on shaft 21 but held against up and down movement by bearings 34 provided therefor. A screw 35 driven by the shaft of an electric motor 38 serves to rotate the wheel 33 at a reduced speed. This motor can be thermostatically controlled as shown.

In practice fuel is placed on the upper grate 3 and will of course cover the agitating element 29. When the motor is started for the purpose of supplying additional fuel, shaft 27 will be rotated and reciprocated and a corresponding movement of the agitator 29 will be set up with the result that the fuel will be thoroughly agitated and will be caused to sift downwardly between the bars of grate 3 and into the fire box 4.

It is to be understood that various other modifications of this invention may be employed.

What is claimed is:

1. In a down draft furnace for boilers or the like the combination with a stationary upper grate and a lower grate forming a combustion chamber therebetween, and a fuel space above the upper grate, of means within the fuel space close to and above the upper grate and positioned for agitating unburned fuel on the upper grate for gravitation through said upper stationary grate into the combustion chamber, and means for automatically operating said agitating means.

2. The combination with a down draft furnace having superposed grates providing a combustion chamber therebetween and fuel receiving space above the upper grate, of a shaft extending into said space, fuel agitating means carried by the shaft and supported adjacent to the upper grate, a motor, and means operated by the motor for actuating the shaft to move the agitating means about the axis of said shaft, said agitating means including a crank extension ex tending from the shaft.

3. The combination with a down draft furnace having superposed grates providing a combustion chamber therebetween and fuel receiving space above the upper grate, of a shaft extending into said space, fuel agitating means carried by the shaft and supported adjacent to the upper grate, a motor, and means operated by the motor for actuating the shaft to move the agitating means about the axis of said shaft, said agitating means including a skeleton wheel and projections on the wheel.

4. The combination with a down draft furnace having superposed grates providing a combustion chamber therebetween and fuel receiving space above the upper grate, of a shaft extending into said space, fuel agitating means carried by the shaft and supported adjacent to the upper grate, a motor, and means operated by the motor for actuating the shaft to move the agitating means about the axis of said shaft, said shaft being tubular and opening outwardly through the casing, there being vents within the shaft for delivering air into the furnace.

GEORGE WILLIAM FRANZHEIM. 

